Death becomes him. Or at least, it consumed composer Christopher Rouse for years.

He's always been a pessimist, the kind of person who responds to good times not by saying, "Life is good," but "Life is not bad." But the passing of several family members and friends over approximately a decade beginning in the mid-'80s pushed him toward the grim output for which he is best known. Musicians of the Baltimore Symphony Orchestra, where he served as composer-in-residence from 1986 to 1989, ironically dubbed him "Mr. Sunshine." His music was agonizing, dissonant and tragic. "Death without transfiguration," he called the overall point of his Symphony No. 1 (1986).

But then even Rouse got tired of the darkness. He made an about-face, writing more blissful pieces, such as his one-movement piece, "Rapture," commissioned by the Pittsburgh Symphony and premiered this weekend. "Rapture," according to Rouse, is an unabashedly joyful work, with a sincerity that cuts from top to bottom. A cynic's joy is a precious metal indeed. Who better to trust about happiness than those folk, bearish on life, who feel it so rarely?

"I am known for writing a very dark, disturbing music," says Rouse (whose name rhymes with "house"). "It just happened that every time I had a piece to write, somebody died whose death had a big effect on me. But I was aware after I wrote the last of that batch of pieces, which was in memory of my mother, that I didn't have any further need to do those. Nobody had died on me; my life had gone death-free."

Rouse, 51, also was unsatisfied with his reputation in the classical music world, feeling "typecast in people's minds as a kind of prince of darkness." The result was a conscious shift: "It occurred to me that I would turn in the other direction, because I am interested in extremes," he says. "I am not interested in writing pieces of music about a plate of ham and eggs."

In the pop music world, a drastic style shift can spell the end of a career. You either are seen as selling out or you simply confuse and alienate your fan base. The practice is more common and artistically feasible within classical music, with a famous example being Beethoven's shift into his heroic phase midway through his life. It resulted in works like the Third and Fifth Symphonies and the "Emperor" Piano Concerto: proof galore that the muse enjoys change.

This would not be the first time Rouse, who won the Pulitzer Prize in 1993, has shifted his compositional aesthetic. He grew up, like most, infatuated with rock and integrated it into several early energetic compositions. One is a percussion work, "Bonham," written in honor of the late Led Zeppelin drummer John Bonham. He also organized an accredited course on the history of rock at the University of Michigan and then at the Eastman School of Music.

"At first [the course] was something of an eyebrow-raiser for some of my colleagues," says Rouse. "It just seemed to me that the time was right, in the late '70s and early '80s ... the people in there didn't really have terribly much memory of rock, before, say the Eagles, so the idea of plunking down the Byrds was a real revelatory experience for them."

He last taught the class in 1985, about the same time he turned his compositional fancy to slower and more tortured textures. The music of this period recalls Shostakovich a bit, which may be why the Shostakovich-loving maestro of the PSO, Mariss Jansons, thinks highly of Rouse's music. "Rapture" is, in fact, dedicated to Jansons.

Of his recent works, Rouse calls the 11-minute "Rapture" "the most light-filled of all." Those who feel that contemporary classical music has offered little in the last four decades might find this work an approachable portal into relevant new music. "It's tonal, not necessarily in the Mozartean sense, but it's full of triads and consonances," says Rouse. "Writing a piece with no dissonance wasn't what I set out to do, but it comes close."

The easy-to-swallow surface is there for programmatic reasons. "It's about a state of spiritual ecstasy -- ever more blinding and active. It begins slowly and gradually gets faster and faster until it ends really in a whirl of prestissimo music."

Though the subject matter of "Rapture" echoes that of several prominent spiritual minimalist composers, such as Arvo Part, John Tavener and Henryk Gorecki, Rouse's piece is decidedly different, according to the composer: "I don't think that anyone would mistake this [for their works] because it's not repetitive, the way Gorecki or Part would be."

And, despite his description of "Rapture" as "spiritual ecstasy," the work is not about the second coming of Jesus Christ. "This not a religious piece, it has nothing to do with the concept of the Rapture," Rouse says. "It's just the notion of a state of almost limitless bliss. If one wants to make it into a religious piece, that's OK. If they want to make it into a secular piece, that's fine."

Composers generally put little stock in titles anyway -- witness the multitude of generic nomenclature, such as symphony or concerto. Names tend to incorrectly bias listeners' opinions prior to hearing the work. "I could've called it 'Ecstasy' but people would've thought I was writing about a drug," says Rouse, jokingly. "There are no good words anymore that haven't been appropriated for some purpose other than what they were originally invented for."

Rouse actually feels that the unapologetic tonality and joyful outlook of "Rapture" may already be a period he is putting behind him. He describes his next work, a clarinet concerto, as "ornery" and "a piece with no consonances." So the cynic in him remains.

"How's it possible not to be a cynic in this day and age?" Rouse says. "But on the other hand there's always the one little ray of hope that somehow things will work out well in the end. I guess I am an agnostic pessimist, in the sense that I am not really sure that pessimism is the ultimate truth."

For now, that little ray of hope is "Rapture," and it behooves us to bask in its rays before the clouds cover the composer's sky again.